The Effect of Tuberculosis Antimicrobials on the Immunometabolic Profiles of Primary Human Macrophages Stimulated with Mycobacterium tuberculosis.

Tuberculosis (TB) remains a global health challenge. Patients with drug-sensitive and drug-resistant TB undergo long, arduous, and complex treatment regimens, often involving multiple antimicrobials. While these drugs were initially implemented based on their bactericidal effects, some studies show that TB antimicrobials can also directly affect cells of the immune system, altering their immune function. As use of these antimicrobials has been the mainstay of TB therapy for over fifty years now, it is more important than ever to understand how these antimicrobials affect key pathways of the immune system. One such central pathway, which underpins the immune response to a variety of infections, is immunometabolism, namely glycolysis and oxidative phosphorylation (OXPHOS). We hypothesise that in addition to their direct bactericidal effect on Mycobacterium tuberculosis (Mtb), current TB antimicrobials can modulate immunometabolic profiles and alter mitochondrial function in primary human macrophages. Human monocyte-derived macrophages (hMDMs) were differentiated from PBMCs isolated from healthy blood donors, and treated with four first-line and six second-line TB antimicrobials three hours post stimulation with either iH37Rv-Mtb or lipopolysaccharide (LPS). 24 h post stimulation, baseline metabolism and mitochondrial function were determined using the Seahorse Extracellular Flux Analyser. The effect of these antimicrobials on cytokine and chemokine production was also assayed using Meso Scale Discovery Multi-Array technology. We show that some of the TB antimicrobials tested can significantly alter OXPHOS and glycolysis in uninfected, iH37Rv-Mtb, and LPS-stimulated hMDMs. We also demonstrate how these antimicrobial-induced immunometabolic effects are linked with alterations in mitochondrial function. Our results show that TB antimicrobials, specifically clofazimine, can modify host immunometabolism and mitochondrial function. Moreover, clofazimine significantly increased the production of IL-6 in human macrophages that were stimulated with iH37Rv-Mtb. This provides further insight into the use of some of these TB antimicrobials as potential host-directed therapies in patients with early and active disease, which could help to inform TB treatment strategies in the future.

Selection of a Single Domain Antibody, Specific for an HLA-Bound Epitope of the Mycobacterial Ag85B Antigen.

T cells recognizing epitopes on the surface of mycobacteria-infected macrophages can impart protection, but with associated risk for reactivation to lung pathology. We aimed to identify antibodies specific to such epitopes, which carry potentials for development toward novel therapeutic constructs. Since epitopes presented in the context of major histocompatibility complex alleles are rarely recognized by naturally produced antibodies, we used a phage display library for the identification of monoclonal human single domain antibody producing clones. The selected 2C clone displayed T cell receptor-like recognition of an HLA-A*0201 bound 199KLVANNTRL207 peptide from the Ag85B antigen, which is known to be an immunodominant epitope for human T cells. The specificity of the selected domain antibody was demonstrated by solid phase immunoassay and by immunofluorescent surface staining of peptide loaded cells of the T2 cell line. The antibody affinity binding was determined by biolayer interferometry. Our results validated the used technologies as suitable for the generation of antibodies against epitopes on the surface of Mycobacterium tuberculosis infected cells. The potential approaches forward the development of antibody in immunotherapy of tuberculosis have been outlined in the discussion.

[Better vaccines against tuberculosis]. / Betere vaccins tegen tuberculose.

In the past 2 years, research on new tuberculosis vaccines and correlates of immunity against tuberculosis has led to significant breakthroughs. This gives real hope for the development and evaluation of effective, life-saving tuberculosis vaccines. These are urgently needed to control the tuberculosis pandemic and to fight increasing multidrug resistance of Mycobacterium tuberculosis. Effective tuberculosis vaccines, as well as more effective drugs and better diagnostics, are the cornerstone of the WHO End TB Strategy.

Efficacy and tolerability of desensitization in the treatment of delayed drug hypersensitivities to anti-tuberculosis medications.

BACKGROUND: Delayed drug hypersensitivity to first-line anti-tuberculosis medication is a major challenge in tuberculosis treatment. OBJECTIVE: This study was performed to investigate the efficacy/tolerability of desensitization therapy in treatment of first-line anti-tuberculosis medication hypersensitivity and the usefulness of immunologic evaluation therein. METHODS: This study was conducted as a prospective, observational cohort study. Subjects who experienced hypersensitivity reactions, including maculopapular exanthema (MPE) and drug reaction with eosinophilia and systemic symptoms (DRESS), to first-line anti-tuberculosis medications (isoniazid [INH], ethambutol [EMB], rifampin [RFP], and pyrazinamide [PZA]) were enrolled. Patch, intradermal, lymphocyte transformation, and oral provocation tests were performed to determine culprit drugs, which were desensitized with rapid and graded challenge protocols. Breakthrough reactions (BTRs) during or after desensitization were assessed. RESULTS: In total, 31 desensitization treatments (INH, 8; EMB, 8; RFP, 11; PZA, 4) to 12 patients (8 with MPE and 4 with DRESS) were performed. The overall success rate of desensitization was 80.7%. All the study subjects except one completed the full course of anti-tuberculosis treatment. The overall BTR free rate was 64.5%. Sixteen (80%) treatments for MPE and four (36.4%) for DRESS were BTR free (P = 0.023). Drugs that were positive on any two of three immunologic studies showed significantly high BTR rates (P = 0.014), although this was not correlated with desensitization failure rate. CONCLUSION: Rapid desensitization therapy to multiple anti-tuberculosis medications for delayed drug hypersensitivity was safe and successful. Combination of multiple immunologic evaluations may predict BTR although it needs validation in larger studies.

Tuberculosis: Smart manipulation of a lethal host.

Tuberculosis (TB) caused by Mycobacterium tuberculosis remains a global threat to human health. Development of drug resistance and co-infection with HIV has increased the morbidity and mortality caused by TB. Macrophages serve as primary defense against microbial infections, including TB. Upon recognition and uptake of mycobacteria, macrophages initiate a series of events designed to lead to generation of effective immune responses and clearance of infection. However, pathogenic mycobacteria utilize multiple mechanisms for manipulating macrophage responses to protect itself from being killed and to survive within these cells that are designed to kill them. The outcomes of mycobacterial infection are determined by several host- and pathogen-related factors. Significant advancements in understanding mycobacterial pathogenesis have been made in recent years. In this review, some of the important factors/mechanisms regulating mycobacterial survival inside macrophages are discussed.

Modulation of autophagy as a strategy for development of new vaccine candidates against tuberculosis.

Effective prevention of tuberculosis (Tb) would undoubtedly be of paramount relevance in the control of its global burden, which resulted in more than 6 million new cases in 2016. Research aimed to improve the current vaccine, Bacillus Calmette- Guérin (BCG), or directed to develop new candidates, has taken into account the interaction between the host and Mycobacterium tuberculosis (Mtb). Recently, autophagy, an intracellular process of the host, has been shown to act as a mechanism that contributes to bacilli clearance in vitro and in vivo. Stimulation of autophagy, if correctly balanced, is an approach that has the potential to enhance the immune response of the host, and offers new avenues for developing immunogens that may give an improved protection upon immunization, given that in fact, some recent rBCG vaccine candidates have been shown to modulate autophagy. In this Discussion, we analyze the role of autophagy in the context of mycobacterial infection, its modulation via mycobacterial elements, and the management of host response as an alternative to develop new, hopefully improved, Tb-vaccine candidates.

Regulatory T Cells Subvert Mycobacterial Containment in Patients Failing Extensively Drug-Resistant Tuberculosis Treatment.

RATIONALE: The advent of extensively drug-resistant (XDR) tuberculosis (TB) and totally drug-resistant TB, with limited or no treatment options, has facilitated renewed interest in host-directed immunotherapy, particularly for therapeutically destitute patients. However, the selection and utility of such approaches depend on understanding the host immune response in XDR-TB, which hitherto remains unexplored. OBJECTIVES: To determine the host immunological profile in patients with XDR-TB, compared with drug-sensitive TB (DS-TB), using peripheral blood and explanted lung tissue. METHODS: Blood and explanted lung tissue were obtained from patients with XDR-TB (n = 31), DS-TB (n = 20), and presumed latent TB infection (n = 20). T-cell phenotype (T-helper cell type 1 [Th1]/Th2/Th17/regulatory T cells [Tregs]) was evaluated in all patient groups, and Treg function assessed in XDR-TB nonresponders by coculturing PPD-preprimed effector T cells with H37Rv-infected monocyte-derived macrophages, with or without autologous Tregs. Mycobacterial containment was evaluated by counting colony-forming units. MEASUREMENTS AND MAIN RESULTS: Patients failing XDR-TB treatment had an altered immunophenotype characterized by a substantial increase in the frequency (median; interquartile range) of CD4+CD25+FoxP3+ Tregs (11.5%; 5.9-15.2%) compared with DS-TB (3.4%; 1.6-5.73%; P < 0.001) and presumed latent TB infection (1.8%; 1.2-2.3%; P < 0.001), which was unrelated to disease duration. Tregs isolated from patients with XDR-TB suppressed T-cell proliferation (up to 90%) and subverted containment of H37Rv-infected monocyte-derived macrophages (by 30%; P = 0.03) by impairing effector T-cell function through a mechanism independent of direct cell-to-cell contact, IL-10, TGF (transforming growth factor)-ß, and CTLA-4 (cytotoxic T-lymphocyte-associated protein 4). CONCLUSIONS: Collectively, these data suggest that Tregs may be contributing to immune dysfunction, and bacterial persistence, in patients with XDR-TB. The relevant cellular pathways may serve as potential targets for immunotherapeutic intervention.

Clinical and Immunological Effects of rhIL-2 Therapy in Eastern Chinese Patients with Multidrug-resistant Tuberculosis.

It is urgent to find an optimised therapy regimen for the control of MDR-TB globally. This study aimed to evaluate the efficiacy and safety of a combined regimen of rhIL-2 injection and standard chemotherapy within 18-month duration in a randomized controlled trial conducted in 14 centres in eastern China. From Jan. 2009 to July. 2016, 271 MDR-TB cases were enrolled and followed up in two groups, 142 cases in study group while 129 cases in control group. Clinical efficacy, safety and immune activity (Th1, Th17, Treg, IFN-γ, IL-17) among the two groups were evaluated and compared. After 24-month following up, cure rate in IL-2 group show higher than that in control group (56% VS 36%, P < 0.01). Rate of mycobacterium clearance (sputum negative) within 3 months was significantly higher in IL-2 group (74% VS 59%, P < 0.05) with no adverse events raised. Patients after rhIL-2 treatment showed increasing of Th1 populations and decreasing of Th17 and Regulatory T cells (Treg) populations, while levels of IL-17A, ROR-γt, and Foxp3 mRNA decreased and level of IFN-γ mRNA increased in PBMCs. Thus, rhIL-2 combined regimen within shorter duration achieved high conversion and success rates and improved Th1/Th17 immune responses, with no safety concerns emerging in MDR-TB patients.

Drug-specific CD4+ T-cell immune responses are responsible for antituberculosis drug-induced maculopapular exanthema and drug reaction with eosinophilia and systemic symptoms syndrome.

BACKGROUND: A multidrug regimen including isoniazid, rifampicin, pyrazinamide and ethambutol is commonly used as first-line treatment for tuberculosis. However, this regimen can occasionally result in severe adverse drug reactions, such as drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome and drug-induced liver injury. The culprit drug and mechanistic basis for the hypersensitive reaction are unknown. OBJECTIVES: To investigate drug-specific T-cell responses in patients with antituberculosis drug (ATD)-induced cutaneous hypersensitivity and its underlying mechanism. METHODS: We enrolled eight patients with ATD-induced maculopapular exanthema and DRESS and performed a lymphocyte transformation test. Subsequently, drug-specific T-cell clones were generated from four of the patients who showed proliferation in response to ATDs. We measured the drug-specific proliferative responses and counted the drug-specific interferon (IFN)-γ/granzyme B-producing cells after drug stimulation. Antihuman leukocyte antigen (HLA) class I and class II blocking antibodies were used to analyse human leukocyte antigen-restricted T-cell responses. RESULTS: Positive proliferative responses to ATDs were mostly found in patients with cutaneous hypersensitivity. Furthermore, we isolated isoniazid/rifampicin-specific T cells from patients, which consisted primarily of CD4+ T cells. Drug-specific CD4+ T cells proliferated and secreted IFN-γ/granzyme B when stimulated with isoniazid or rifampicin, respectively. Isoniazid-responsive T-cell clones did not proliferate in the presence of rifampicin and vice versa. Drug-specific T-cell responses were blocked in the presence of anti-HLA class II antibodies. CONCLUSIONS: This study identifies the presence of isoniazid/rifampicin-specific T cells in patients with ATD-induced maculopapular exanthema and DRESS. Furthermore, it highlights the important role of drug-specific T-cell immune responses in the pathogenesis of these reactions.

From the Cover: Characterization of Isoniazid-Specific T-Cell Clones in Patients with anti-Tuberculosis Drug-Related Liver and Skin Injury.

Isoniazid, rifampicin, pyrazinamide, and ethambutol are commonly used for the treatment of tuberculosis. Drug exposure is occasionally associated with liver and/or skin injury. The aim of this study was to determine whether drug-specific T-cells are detectable in patients with adverse reactions and if so characterize the nature of the T-cell response. Peripheral blood mononuclear cells (PBMC) from 6 patients with anti-tuberculosis drug-related adverse reactions (4 liver, 2 skin) were used to detect drug-responsive T-lymphocytes. Positive lymphocyte transformation test and/or ELIspot results were observed with all 6 patients. Over 3400 T-cell clones were generated from isoniazid, rifampicin, pyrazinamide, or ethambutol-treated PBMC. CD4+ clones from all 3 patients were activated to proliferate and secrete cytotoxic mediators (granzyme B, perforin, FasL) and effector (IFN-γ, Il-13) and regulatory (Il-10) cytokines with isoniazid, but not rifampicin, pyrazinamide, or ethambutol. Il-17 was not detected, while only 1 clone secreted Il-22. Isoniazid-responsive clones were not activated with other anti-tuberculosis drugs or isonicotinic acid albumin adducts. Activation of the clones with isoniazid was MHC class II-restricted and dependent on antigen-presenting cells. Most clones were activated rapidly even in the presence of the enzyme inhibitor 1-aminobenzotriazole. However, a time-dependent pathway of activation involving auto-oxidation of isoniazid was also observed. The discovery of isoniazid-specific CD4+ T-cell clones in patients with liver and skin injury suggests that the adaptive immune system is involved in the pathogenesis of both forms of iatrogenic disease.

Positive allergy study (Intradermal, patch, and lymphocyte transformation tests) in a case of isoniazid-Induced DRESS

No disponible

Protective and therapeutic effects of the resuscitation-promoting factor domain and its mutants against Mycobacterium tuberculosis in mice.

The resuscitation-promoting factor (Rpf), a secretory protein first reported in Micrococcus luteus, plays a critical role in mycobacterial survival and infection. There are five functionally redundant Rpf-like proteins identified in M. tuberculosis (Mtb). All these Rpfs share a conserved Rpf domain (Rpfd) composed of approximately 70 amino acids, which possesses the same biological functions as the full-length Rpf protein. Glutamic acid at position 54 in Rpfd (E54) has been implicated in mediating multiple physiological processes, and a single amino acid substitution at residue E54 can affect the protein biological activity. In order to determine the effects of different amino acid substitutions of E54 in Rpfd on its immunogenic activity, we generated three recombinant Rpfd mutants, Rpfd1 (E54K), Rpfd2 (E54A) and Rpfd3 (E54K and D48A), based on T-cell epitope prediction and tested their potential protective/therapeutic effects against Mtb in mice. Our results demonstrated that replacement of E54 by different amino acids in Rpfd distinctively influenced its resuscitation-promoting activities and Th1-type immune responses induced in mice. Administration of Rpfd2 mutant enhanced Th1-type cellular responses (IFN-γ and IL-2) in mice (P < 0.05, Rpfd2 versus control) and provided effective protection against Mtb in mice by significantly inhibiting the growth of Mtb during the initial stage of infection. Four weeks after the challenge, the slightest pathological injury in lung was observed in the Rpfd2-immunized group among all three Rfpd mutant-immunized groups. Furthermore, Rpfd2 therapy significantly decreased the bacterial load in lung and alleviated histopathological damage in Mtb-infected mice. Together, our results suggest Rpfd2 as a novel effective vaccine candidate against Mtb.

Autophagy in the fight against tuberculosis.

Tuberculosis (TB), a chronic infectious disease mainly caused by the tubercle bacillus Mycobacterium tuberculosis, is one of the world's deadliest diseases that has afflicted humanity since ancient times. Although the number of people falling ill with TB each year is declining, its incidence in many developing countries is still a major cause of concern. Upon invading host cells by phagocytosis, M. tuberculosis can replicate within infected cells by arresting the maturation of the phagosome whose function is to target the pathogen for elimination. Host cells have mechanisms of controlling this evasion by inducing autophagy, an elaborate cellular process that targets bacteria for progressive elimination, decreasing bacterial loads within infected cells. In addition, autophagy activation also aids in the control of inflammation, contributing to a more efficient innate immune response against M. tuberculosis. Several innovative TB therapies have been envisaged based on autophagy manipulation, with some of them revealing high potential for future clinical trials and eventual implementation in healthcare systems. Thus, this review highlights the recent advances on the innate immune response regulation by autophagy upon M. tuberculosis infection and the promising new autophagy-based therapies for TB.

Drug reaction with eosinophilia and systemic symptoms syndrome is not uncommon and shows better clinical outcome than generally recognised.

BACKGROUND: Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare disease which can cause severe morbidity and mortality. The aim of this study is to evaluate the clinical manifestation and course of DRESS syndrome. METHODS: We conducted a retrospective analysis of prospectively collected data in 45 patients with DRESS syndrome diagnosed between September 2009 and August 2011. RESULTS: The most common causative drug group was antibiotics (n=13, 28.9%), followed by anticonvulsants (n=12, 26.7%), antituberculosis drugs (n=6, 13.3%), non-steroidal anti-inflammatory drugs (n=4, 8.9%), undetermined agents (n=4, 8.9%), allopurinol (n=3, 6.7%), and others (n=3, 6.7%). The latency period ranged from 2 to 120 days, with a mean of 20.2 ± 24.3 days. The longest latency period was noted for the antituberculosis drug group, at 46.5 ± 29.9 days. Eosinophilia in peripheral blood examination was noted in 35 subjects (77.8%). Atypical lymphocytosis was noted in 16 patients (35.6%), and thrombocytopenia in seven patients (15.6%). Hepatic involvement was noted in 39 (86.7%) study patients, kidney in eight (17.8%), lung in four (8.9%), and central nervous system in one (2.3%). Systemic corticosteroids were administered to 10 patients (22.2%). Forty-three patients (95.6%) showed complete recovery, while two patients had poor outcomes. CONCLUSIONS: DRESS syndrome was not more uncommon than generally recognised. Antibiotics were the most frequently implicated drug group, followed by anticonvulsants. Most patients with this disease showed a better clinical outcome than that which had been generally expected.

Antigen-specific interferon-gamma responses and innate cytokine balance in TB-IRIS.

BACKGROUND: Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) remains a poorly understood complication in HIV-TB patients receiving antiretroviral therapy (ART). TB-IRIS could be associated with an exaggerated immune response to TB-antigens. We compared the recovery of IFNγ responses to recall and TB-antigens and explored in vitro innate cytokine production in TB-IRIS patients. METHODS: In a prospective cohort study of HIV-TB co-infected patients treated for TB before ART initiation, we compared 18 patients who developed TB-IRIS with 18 non-IRIS controls matched for age, sex and CD4 count. We analyzed IFNγ ELISpot responses to CMV, influenza, TB and LPS before ART and during TB-IRIS. CMV and LPS stimulated ELISpot supernatants were subsequently evaluated for production of IL-12p70, IL-6, TNFα and IL-10 by Luminex. RESULTS: Before ART, all responses were similar between TB-IRIS patients and non-IRIS controls. During TB-IRIS, IFNγ responses to TB and influenza antigens were comparable between TB-IRIS patients and non-IRIS controls, but responses to CMV and LPS remained significantly lower in TB-IRIS patients. Production of innate cytokines was similar between TB-IRIS patients and non-IRIS controls. However, upon LPS stimulation, IL-6/IL-10 and TNFα/IL-10 ratios were increased in TB-IRIS patients compared to non-IRIS controls. CONCLUSION: TB-IRIS patients did not display excessive IFNγ responses to TB-antigens. In contrast, the reconstitution of CMV and LPS responses was delayed in the TB-IRIS group. For LPS, this was linked with a pro-inflammatory shift in the innate cytokine balance. These data are in support of a prominent role of the innate immune system in TB-IRIS.

[Preparation of an autophagy-targeted antituberculosis DNA vaccine encoding LpqH fused with LC3].

OBJECTIVE: To construct an autophagy-targeted vaccine harboring the genes encoding lipoprotein antigen precursor LpqH from Mycobacterium tuberculosis and microtubule-associated protein light chain-3(LC3), and to investigate its efficacy of inducing and targeting autophagy. METHODS: The expressions of LC-3 and LC3-LpqH in RAW264.7 cells were detected by Western blotting after transfected with pCMV-LpqH and pCMV-LC3-LpqH plasmids respectively. The pCMV-LC3-LpqH or pCMV-LpqH plasmids were transfected into GFP-LC3-RAW264.7 cells to analyze the localization of LC3-LpqH by immunofluorescence staining. RESULTS: After transfected with pCMV-LpqH DNA, RAW264.7 cells showed a significant increase of LC-3 amount. The LC3-LpqH fusion protein was also detected in RAW264.7 cells after pCMV-LC3-LpqH transfection and in a dose-dependent manner. Interestingly, LpqH was found to be transported to autophagosomes through the fusion protein, which was demonstrated by the co-localization of GFP-LC3 and LC3-LpqH on autophagosomes. CONCLUSION: The recombinant plasmid encoding pCMV-LC3-LpqH could enhance the autophagy in vitro, and facilitate the localization of LpqH on autophagosomes. Our study provides a new practical strategy for the development of improved vaccines against Mycobacterium tuberculosis.

Getting personal perspectives on individualized treatment duration in multidrug-resistant and extensively drug-resistant tuberculosis.

Tuberculosis (TB) differs from most other bacterial infectious diseases by a very long duration of combination antibiotic therapy required to achieve relapse-free cure. Although the standard recommended "short-course" treatment length for TB is 6 months, the World Health Organization recommends a duration of 20 months for the treatment of patients with multidrug-resistant and extensively drug-resistant TB (M/XDR-TB). Apart from the long duration of anti-TB therapy, treatment of M/XDR-TB is very expensive and often associated with adverse drug events. The optimal duration for treatment of TB likely differs between individuals and depends on a variety of variables, such as the extent of the disease, the immune status of the host, and the virulence and the drug resistance of the causative strain of Mycobacterium tuberculosis. Some patients with M/XDR-TB may have to be treated with currently available antituberculosis drug regimens for more than 20 months, whereas much shorter treatment durations may be possible to achieve cure for the majority of patients with M/XDR-TB. Personalization of the duration of treatment for TB, especially for patients with M/XDR-TB, would be highly desired. Until recently there has been little interest in the identification of biosignatures that could eventually lead to individual recommendations for the duration of anti-TB therapy. This pulmonary perspective reviews the knowledge on clinical and radiological scores, host- and pathogen disease-related profiles, molecules, and signatures that are currently explored as biomarkers to personalize the duration of therapy in TB.

IgG3 is the dominant subtype of anti-isoniazid antibodies in patients with isoniazid-induced liver failure.

Isoniazid (INH) therapy is associated with a significant incidence of idiosyncratic liver failure. We recently reported eight cases of INH-induced liver failure in which patients had antidrug and anticytochrome P450 antibodies. However, it was unclear what role these antibodies play in the mechanism of INH-induced liver injury. Here, we report that the dominant isotype of anti-INH antibodies was IgG, with IgG3 being the dominant subtype. IgG3 antibodies are associated with a Th1-type immune response and fix complement. IgG3 antibodies have been associated with other forms of liver injury and may play a pathogenic role in INH-induced liver injury.

Anti-tuberculosis treatment enhances the production of IL-22 through reducing the frequencies of regulatory B cell.

IL-22 has been suggested to play an important role in immune response against Mycobacterium tuberculosis infection. However, the exact role of IL-22 in human tuberculosis (TB) infection remains unclear and the regulatory mechanism of IL-22 response in human TB is unknown. In this study, we observed that successful anti-tuberculosis treatment induced an enhanced and sustained M. tuberculosis antigen-specific IL-22 response, correlated with the decrease of the frequencies of CD19(+)CD5(+)CD1d(+) regulatory B cells. We also found that depletion of CD19(+) B cells significantly enhanced M. tuberculosis antigen-specific IL-22 production by peripheral blood mononuclear cells. More importantly, we observed that purified CD19(+) B cells, and more efficiently, CD19(+)CD5(+)CD1d(+) regulatory B cells, suppressed IL-22 production. In summary, we showed here for the first time that effective anti-tuberculosis treatment restores M. tuberculosis antigen-specific IL-22 response through a novel mechanism by reducing the frequencies of CD19(+)CD5(+)CD1d(+) regulatory B cells in human TB.